What Causes Hot Tub Foam? (and how to get rid of it)

Is your hot tub filling up with some annoying foam? Have no fear! It’s quite natural that your hot tub will generate some foam over time. But when that happens, most of us wonder what causes hot tub foam and how do I get rid of hot tub foam.

Here’s what I’ve learned in owning 4 hot tubs:

Hot tub foam is a signifier of a chemical imbalance in your hot tub. It may be that the pH is too high, but also, over time, sweat, lotions, dirt, perfumes & deodorants can rub off into the water and lead to foam. Keeping the water chemistry balanced and changing the water every 3 months can help eliminate foam.

But there’s a lot more to know than that! So let’s keep going.

In this post, we’ll also get into how to tell if you can simply treat foamy water or if it’s time to change it. And we’ll also talk about my favorite defoamer product which works on small amounts of foam.

The good old days of splashing around in a mountain of bubbles are gone. As a child, it may be exciting to bathe in the magical bubbles, but in a hot tub, these bubbles are off-limits. Your children may be excited about an outdoor bubble bath, but don’t let them soak in it!

Foaming in hot tubs and spas is a problem encountered by almost every spa owner at some point in time.

Even with regular sanitation and filtration, foamy hot tub water can still appear and cause trouble. If there is more than a thin layer of foam, it’s time to get to work and get rid of it!

Keep on reading to find out how to get rid of the foam in your hot tub, and what causes it!

Why do I have so much foam in my hot tub?

The foam that appears in hot tubs is not harmful.

It is simply a buildup of products and Total Dissolved Solids (TDS) in the hot tub’s water. Hot tub foam is caused by “full” or old water.

If your water is like this, and you turn on your jets, it is likely foam will appear in your hot tub water. Or if it was already there, the jets will make it worse.

Several different products can cause hot tub foam if they get rubbed off our skin into the water.

These include:

  • Soap
  • Laundry detergent
  • Makeup
  • Cosmetics
  • Deodorant
  • Body lotions
  • Body oils
  • Shampoo
  • Conditioner

And it should go without saying that the hot tub is no place for bubble bath, no matter how much your friends think that’s a good idea.

Additionally, low calcium levels (the hardness of the water) in your spa can decrease the surface tension of your spa’s water, which in turn allows for excessive foaming on the water.  But, low calcium levels in your water can damage your hot tub in other ways too.

Any imbalance in your water is bad.

It can cause your water to turn green, smell bad, and can cause foam to form. Additionally, filling your water with soft water is a bad idea. It can have several negative effects. If you have a water softener, turn it off when you fill it, as it can increase the chance of hot tub foam being created.

Spa systems and hot tubs make bubbles and a bit of foam all the time. To ensure that you have an actual foam problem, follow these quick steps.

Run your jets for a few minutes until the natural bubbles and foam appear. Then turn your jets off and wait a minute or two. If the bubbles/foam are still there after a minute or two, then you have a problem.

The bubbles should be very large and sticky to the touch.

Is foam in a hot tub bad?

There is a big difference between foam and bubbles in your hot tub. Bubbles are made when water and air are mixed together and sent through the jets of the hot tub by a jet pump.

Foam in your hot tub or spa occurs because of jet bubbles holding their shape after the jets have been turned off. Foam is formed due to the contaminants in the water. These contaminants include body oil, sweat, dirt, suntan lotion, soap, deodorant, shampoo, conditioner, makeup, and laundry detergent.

Foam in your hot tub is not harmful, but it is not recommended to soak in. In fact, you should never enter a hot tub with foam, it is a clear indicator that the sanitation is not being properly maintained.

If you come home after a long day, desiring a soak, and find foam in your hot tub, you’ll have to wait to soak.

Over time, this imbalance, if left untreated, can damage your hot tub. Certain parts of the equipment can be corroded, and walls can be discolored.

But don’t panic, it is easy to get rid of this!

Not sure how often you should be changing your water in your hot tub?

That’s a great question! And for the long-term wear and tear on your equipment and the health of the people using the hot tub, you must change it on schedule!

You should change yours every 3-5 months. Why the range? It depends on several factors, and I get into all of them in a recent article that explains how to know what’s right for your hot tub. I even explain how to tell when it’s time just by looking at it.

Just click that link to read it on my site.

Does high pH cause hot tub foam?

Yes is the short answer, but it’s not the only cause. There are a lot of different factors that can cause your hot tub to foam up.

The pH balance is certainly one of them. Cloudy and foamy water indicates that the chemical balance in your hot tub water is imbalanced.

If your water is cloudy or foamy, it’s best to also check the pH levels in the water. Use a chemical test kit to check the pH levels.

Water with a pH level that is greater than 7.8 is too high.

Additionally, if your water’s alkaline levels are higher than 120, it is too alkaline. Either of these issues, high alkalinity or high pH, can cause cloudy water. High pH can also be the cause behind hot tub foam.

In a recent article, I walk you through all my

You should add a Calcium Increaser (click to see my favorite one on Amazon) if your calcium hardness level is less than 200 ppm. If your Total Alkalinity level is less than 100 ppm, then you should add an Alkalinity Increaser (click to see my favorite one on Amazon).

Finally, to keep your pH level between 7.4 and 7.6 ppm, add pH Up or pH Down.

Not sure if it’s safe to use a hot tub if the pH is too high?

All hot tub chemicals are designed to operate within a range. So it’s not that you have to hit 1 exact number. But what happens when the pH is too high and is that even safe to use?

Luckily, I break it all down simply in a recent article. I explain the range, and some tell-tale symptoms you can spot to know if your pH is too high.

Just click that link to read it on my site.

How much foam is normal in a hot tub?

There should be zero foam in a hot tub.

Hot tubs are not bubble baths, they should not have foam. Bubbles are naturally occurring in hot tubs, and there is a large difference between bubbles and foam.

While the foam is harmless to humans, it is an indicator of an underlying issue or issues with your hot tub.

As previously stated, you will want to check the chemical balance of your hot tub. Use a chemical test kit to check the pH levels. Water with a pH level that is greater than 7.8 ppm has too much pH in it.

Low calcium levels in your spa can decrease the surface tension of your spa’s water. This allows excessive foaming on the water to occur.

Additionally, low calcium levels in your water can damage your hot tub.

Using test strips is a really easy and effective way of figuring out your hot tubs chemical balance. To use a test strip, just dip it in the hot tub water.

Then wait fifteen seconds. The test strip will turn into a color, and you should compare the color that appeared with the color guide that came with the test strip. Then just balance chlorine/bromine, pH, alkalinity, stabilizer, and any other measures shown on your test strips.

Foam can damage the hot tub equipment, so it is best to take care of this issue immediately.

Confused about pH and alkalinity?

You’re not alone. After all, while they are related and one affects the other, they are also 2 totally different things.

Luckily, I break it all down simply in a recent article. I explain each one, how one affects the other, and how to balance your water correctly.

Just click that link to read it on my site.

Do I have to drain my hot tub to get rid of the foam?

For small amounts of foam, no.

Once you see foam and or cloudiness, test the water level of your hot tub. Adjust the water chemistry as needed and run the jets.

You can also use a defoamer such as my favorite one, Leisure Time HQ Spa Foam Down (click to see it on Amazon).

If you want to try something to get rid of the foam before completely emptying your hot tub’s water, purchase some sanitizer (if you don’t have any already).

Pour extra sanitizer into the hot tub, it may help to break down whatever is making your hot tub foamy (this will only work if the chemical levels are balanced yet the hot tub is still foamy). Also, try adding an extra dose of chlorine to your water.

Run your jets for forty-five minutes to an hour. Wait two minutes after turning off the jets, then activate them again. If the foam does not appear, success! Make sure to take out your filters and either clean them thoroughly or put in new ones.

Unfortunately, if foam remains, the best way of getting rid of it is to completely drain your water. Additionally, you may also need to remove and replace your hot tub filter.

How often do you need to change your filters and do you need to clean them periodically?

Filters need to be changed only once every 1-2 years. But that range depends not only on how often you use the hot tub, but how well you maintain the filters each month.

After all, you should be doing monthly and quarterly cleanings too. Luckily I cover how you can do all of that quickly and easily in a recent article.

Just click that link to read it on my site.

How do I stop my hot tub from foaming?

There are a lot of ways to prevent your hot tub from foaming.

1. Shower before soaking in your hot tub

Showering before entering your hot tub ensures that you won’t bring in anything that is clinging to your body, such as sweat, lotions, dirt, perfumes, colognes, deodorants, and oils.

All of those things can cause hot tubs to foam. If you don’t wear a lot of products on your body, you can skip showering before entering the hot tub.

2. Use a clean bathing suit

A second step to prevent your hot tub from foaming is to ensure your bathing suit is rinsed clean before soaking in your spa. Any bathing suit fresh out of the washer and dryer is covered in laundry detergent. Wash your bathing suit with fresh water and let it dry before entering your hot tub.

3. Keep your spa water well-balanced

A third way of preventing foam in your hot tub is to make sure you are using high-quality chemicals. Do your research on different brands used for hot tubs. Cheap chemicals have fillers in them, which in turn makes you have to pour in more of the chemical in your hot tub.

Chlorine-free spa shock should also be used weekly.

It is chemical-free and helps oxidize your hot tub water. It will also ensure body oils, lotions, colognes, deodorants, creams, and makeup are broken down.

A defoamer specifically designed for use in a hot tub will get rid of these excess substances. My favorite one for that is Leisure Time HQ Spa Foam Down (click to see it on Amazon).

4. Keep long hair tied back

You should also tie long hair back to prevent it from entering the water. This will ensure hair products such as shampoo, conditioner, gel, mousse, and hair spray are not transferred into the hot tub or spa water.

5. Avoid eating or drinking in the hot tub

Make sure you don’t eat or drink near your hot tub!

Spilled solids and liquids can lead to foaming. If you do eat and drink near it, be very careful not to spill anything into the water. A good way of preventing this is to purchase a hot tub accessory that floats on the water and lets you store food and drink on it.

6. Skip the tanning lotions

Also, avoid using fake tanning products.

They are easily stripped off of your skin and go right into the water. These products turn your hot tub shell, pipework, and other internal systems of the hot tub green or brown!

7. Open the lid regularly

Finally, you will want to open your hot tub’s cover regularly.

This will help prevent foam from forming because it allows oxygen to be introduced into your water. Also, ensure you take out any foreign debris such as leaves or twigs that enter your hot tub. These can break down and cause hot tub foam.

Did I cover all you wanted to know about hot tub foam and what causes it?

The foam that appears in your hot tub is not harmful to humans.

It can, however, damage your hot tub over time, and it is not recommended to soak in. Foam should never be in your water, as it is an indicator that something is wrong with the chemical levels in your hot tub.

Test the pH with a chemical test kit, a high pH can cause this. If the pH is above 7.8, then your pH level is too high.

Additionally,  low levels of calcium in your hot tub can decrease the surface tension of your spa’s water. Low surface tension can allow foam to be created. Low calcium levels in your hot tub can also damage your spa’s internal systems.

Many contaminants cause hot tubs to generate foam.

The majority of these contaminants come from your own skin or body. Your hair may be filled with hair products such as cream, mouse, and hairspray, so tie long hair back to ensure it does not touch the water.

There are other contaminants on your body. These include deodorant, cologne, fake tanning products, sweat, dirt, perfume, lotion, and other oils. All of these help cause foam to appear in your hot tub.

Keeping your water and filters changed on schedule and monitoring your water chemistry weekly are the best ways to avoid hot tub foam.

For large amounts of foam, you will most likely have to drain your hot tub’s water to get rid of the foam.

The more your hot tub is used, and the more people that use the hot tub, the more likely you are to develop a foam problem.

Not sure of the best way to drain your hot tub or if it’s OK to drain it on your lawn?

Luckily, I have a recent article where I get into the best way to do it in under 15 minutes, and how to do it without damaging grass or trees.

Just click that link to read it on my site.


Photo credits which require attribution:

Party @ The Exchange by Coy! is licensed under CC2.0

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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